Independent insertion devices controlled off-line from image forming apparatuses are known. Such insertion devices are capable of insertion of a large amount of enclosures on which the image forming apparatuses form images into designated envelopes.
JP-2007-008653-A proposes an insertion system that inserts sealed sub-envelopes that contain enclosures as well as other enclosures into main envelopes. The insertion system includes multiple enclosure feeding units arranged serially along conveying means in the direction in which enclosures are transported. To accommodate different types of enclosures, the number of enclosure feeding units is identical to the number of enclosure types.
However, in the above-described system in which the insertion device is controlled off-line from the image forming apparatus, image formation on enclosures and insertion of those enclosures in envelopes are performed by separate devices. Accordingly, it is necessary to set enclosures as well as envelopes and input insertion procedure for each combination of enclosures and envelopes. Therefore, in the case of small lots, frequency of setting of enclosures as well as envelopes in the device and input of insertion procedure is high, increasing down time.
In view of the foregoing, various approaches are tried. To eliminate the down time in small-lot insertion processing, for example, the image forming apparatus and the insertion device may be controlled online so that the printed enclosures and envelopes can be transported from the image forming apparatus to the insertion device. In this configuration, preparation of enclosures on which images are formed and insertion of enclosures into envelopes can be performed in succession.
This system, however, has a drawback when there are enclosures other than those output from the image forming apparatus. More specifically, although an inserter or enclosure supply device is used to feed such enclosures to the insertion device, the number of feed cassettes of the enclosure supply device is small compared with the size of the device. Therefore, when the number of enclosure types is greater than the number of feed cassettes of the enclosure supply device, it is necessary to divide a single job and change the enclosure type set in the enclosure supply device for each divided job, or it is necessary to visually check the combination of enclosures and envelopes. Therefore, operability as well as productivity in insertion of enclosures into envelopes is reduced.
Additionally, because a single enclosure feeding unit contains only a single type of enclosure in the above-described system proposed in JP-2007-008653-A, when the number of enclosure types is greater than the number of enclosure feeding units, insertion of different enclosure types cannot be completed in a single job, and thus the job must be divided. Although the number of enclosure feeding units may be increased so that insertion of different enclosure types can be completed in a single job, doing so increases the size of the system in the dimension along which enclosures are transported, which is not desirable.